Seiko SBBN017: Real Tuna and Tuna Style

Today I will talk about a real Seiko classic: The watches with the nickname “Tuna”. The Tuna is very, very Seiko – there is no watch from any other brand with a similar look. It’s a real classic, the first Tuna appeared 1975. And like all real classics, there are cheap Chinese look-a-likes or better: wanna-bees. I don’t like the word “hommage”, they are just cheap copies from companies without any own idea.

Looking at the recent collection we have a broad variety of Tunas in Seiko’s portfolio. On one hand we have the Marinemaster Tunas with 300m, 600m or even 1,000 m water resistance with prices above 1,000 Euro, most of them with quartz, some with mechanical movements. On the other hand we have the far more affordable Solar-Tunas in various colours and various stlyes (Divers and Street-Style). And there is the New Arnie which looks similar to a Solar Tuna, but has different historic roots and a different solar quartz movement. I think we count the New Arnie out, it’s not a Tuna (more about the New Arnie in my entry: https://michaelswatchblog.de/2019/10/18/why-the-new-arnie-snj025-is-my-favorite-seiko-release-2019/).

But are the Solar Tunas “real” Tunas? Not for me…but to understand this we first must have a look at the history and the technical features to define the characteristics of a real Tuna.

In 1968 Seiko received a letter from a Japanese diver complaining about Seiko divewatches not good enough for saturation diving. So the Seiko management gave order to Ikuo Tokunaga and his team of engineers to develop “the perfect professional diver’s watch”. Seven years and more than 20 patents later they presented the first Tuna 6159-7010, with a mechanical movement. It was the first diver’s watch with
– a titanium monocoque case
– a titanium shroud with ceramic coating to protect glass and case
– an L-shaped gasket for water resistance and
– a vented rubber strap
While other watches for saturation diving featured helium escape valves to let helium and other gases out again (Rolex and Doxa invention), Seiko decided to shut the watch tighten so no gas could get inside the watch from the beginning. The screw-down retaining system and the shroud gave the watch the nickname “Tuna can”, or short “Tuna”.

In 1978 Seiko replaced this “Grandfather Tuna” by the Golden Tuna 7549, the first Tuna with a quartz movement. From now on most Tunas have quartz movements.

Golden Tuna 7549
7549 Movement (picture by ajiba54)
Golden Tuna 7549 and Golden Tuna Reissue 7C46 (picture by ajiba54)

Today a 7C46 is used. There are still Tunas with mechanical movements (Seiko’s best 8L-movements) but most collectors would agree with my statement: The typical Tuna is a quartz watch. This movements were and are high-quality movements, you can’t compare them with today’s usual cheap full-plastic movements (even from Seiko). The 7C46 is a plastic/metal hybrid movement, adjustable, with 7 jewels and a high torque motor to move the heavy and big hands of the Tunas. On the other side this movement uses an ordinary quartz battery which is available all over the world. And it needs very few power. Seiko guarantees a five year battery life but mostly you’ll have to change the battery after 7-10 years. There is a scale engraved at the caseback where a watchmaker can mark the quarter/year of the battery change. And if power runs low, the second hand jumps two seconds at once. This is a professional movement for a professional watch. No need to thrill up your nose if you only like mechanical movements! The Tuna is therefore a real professional watch: highly reliable, highly legible and almost undestructible.

Of course with this construction Tunas are nothing but small watches. The smallest 300m Tunas have a diameter of ca. 47,5mm. But have in mind, that Tunas don’t have real lugs (just stubs). So the watch dimension is not only 47,5mm from left to right but also from up to down. Believe me, the 300m Tuna is one of my most comfortable watches on my 17,5 cm wrist! Ok, the 1,000m Tunas with a diameter of ca. 51,5mm might be a bit too big for many people (including me).

My SBBN017 on my 17,5cm wrist

Let’s now look at the Solar Tunas, which appeared about 3 or 4 years ago. The movement is a V157 solar quartz movement. That’s a good movement, ok, but in no way like a 7C46. It’s a rather simple quartz movement, used in many Seiko quartz watches. It’s not adjustable, contains no jewels and is made of plastic. The Solar Tuna might look like a Tuna, but contains no L-gasket, the shroud is made of hardened plastic (the professional Tunas have metal or ceramic shrouds) and the movement is rather simple. They have a 200mm water resistance. The Prospex sign on the dial classifies them as ISO-Divers. But nethertheless they are a lot more fragile with their built-in solar panels and the plastic movement. So if you are thinking about getting a real Tuna for about 1/3 the price of a professional Tuna – forget it.

Solar Tuna SNE498

If you are looking for a cool watch with interesting design and no battery change for normal every day use, the Solar Tuna might be a good choice for you. What they have in common with their big brothers is a very comfortable feeling on the wrist and high legibility day and night. But the differences are far greater than the common grounds.

A serious Seiko collector should have a “real” professional Tuna in his collection. You can get one for about 1,200 Euro. That’s a very very good price for a high quality professional watch.

SBBN017 on an Erikasoriginals
Lume on the Solar Tunas is equal good as on the Professional Tunas
Caseback of my SBBN017 with year/quarter marks
Most Tunas are JDM models with Kanji dials
Lugs? What lugs?
Shroud 1
Shroud 2
Signed crown (only old Tunas)
The other Marinemaster
Lume pip
Heavy hands
Domed Hardlex
SBBN017